I guess I would try freezing it and sending it in a cheep little styro sixpack cooler. He must be a special nephew, to get such preferential treatment! You could use an unopened bag of chips to insulate the box.

I only will eat fresh myself. Lucky nephew! :) How about just putting it in a thermos like container and shipping it to him overnight. The faster it got there the less chance of it becoming rancid in the process.Or maybe even vacumn packing it and getting ahold of some of those refridgerator bags to pack around it.

My thought was if you make it fresh, pack it in a styrofoam container (leakproof) with some dry ice, and then send overnight, it would probably make it fine. Lucky Nephew.... if you don't have anywhere else to send that yummy salsa, I'll give you my address!